title: Disseminated colorectal tumor cells in organs prone to metastasis detected by new double enriched nested-PCR in comparison with recognized assays.
abstract: Hypothetically, K-ras mutations can be used as a marker of disseminated tumor cells (DTCs) in patients with K-ras mutated primary carcinoma. This study focused on the development of a useful assay for detecting low numbers of DTCs in potential target tissues of metastatic K-ras codon 12 mutated colorectal cancer. Tumor, liver, lymph node and bone marrow tissues from 46 colorectal carcinoma patients were examined for K-ras codon 12 mutations with a new double enriched nested (DEN)-PCR and the incidence of mutations was compared to those obtained from three established assays. DEN-PCR followed by sequencing found one mutated cell within 107 K-ras codon 12 wild-type cells and was more sensitive than other methods (1:106-1:102). Colon carcinomas (26/46) and adenomas (1/3) harbored mutations in K-ras codon 12. Sixteen of these 27 mutated tumors were found with all assays, two with three methods and one with the two most sensitive assays. In 8 cases, only DEN-PCR identified the K-ras mutation, and thus prevailed over the other methods used (p<0.002). Eight of 26 patients with K-ras mutated colorectal carcinoma also harbored K-ras mutated DTCs in liver and lymph nodes, respectively, and 4 in bone marrow. For liver and lymph node samples, DTC-mutations were identical to those in the primary carcinoma but those in bone marrow differed from the respective mutation in the primary carcinoma. In conclusion, DEN-PCR is a highly sensitive method for detecting K-ras mutations as marker of early and late tumor cell dissemination in tissues potentially harboring colorectal carcinoma metastases.
authors.affiliation: Toxicology and Chemotherapy Unit, German Cancer Research Center, D-69120 Heidelberg, Germany.
authors.forename: Magdalena C
authors.initials: MC
authors.lastname: Kraus
authors.forename: Ulrich
authors.initials: U
authors.lastname: Linnemann
authors.forename: Martin R
authors.initials: MR
authors.lastname: Berger
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009362:Neoplasm Metastasis / Q000175:diagnosis*; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor